The Dichroicon: Spectral Photon Sorting For Large-Scale Cherenkov - PowerPoint PPT Presentation

The Dichroicon: Spectral Photon Sorting For Large-Scale Cherenkov and Scintillation Detectors Tanner Kaptanoglu University of Pennsylvania DUNE Module of Opportunity Workshop November 2019

Provide Photon Wavelength Information for Large-Scale Neutrino Detectors For water Cherenkov detectors the scale of For scintillator or water-based Hyper-K, dispersion can spread photon arrival scintillator detectors, measuring times by > 2 ns. Measuring time between long wavelength provides information about and short wavelength photons provides the process that created the photon information about event position (Cherenkov or scintillation) Theia Hyper-K

Cherenkov Light in a Liquid Example timing in large Cherenkov ring on top of neutrino detector isotropic scintillation light Scintillator Detector B. Land ➢ Charged particle traveling through liquid scintillator creates both scintillation (~10,000 photons/MeV) and Cherenkov light (~100 photons/MeV) ➢ Challenge is to detect the Cherenkov light, which provides the direction of the traveling particle. Typically A. Mastbaum use timing and directionality. ➢ High light yield from scintillator provides excellent SNO+ Collaboration energy and position resolution and low energy thresholds ➢ Cherenkov light allows one to reconstruct direction, Expected background improve particle ID for SNO+ 0νββ dominated by solar neutrinos ➢ Many applications towards future experiments: Neutrinoless double beta decay, low energy solar neutrinos, reactor and geo antineutrinos, atmospheric neutrinos, long baseline physics R. Bonventre, G.D. Orebi Gann, Eur. Phys. J. C (2018) 78:435 CNO sensitivity improves with improved direction reconstruction Schematic from J. Klein

Separating Cherenkov and Scintillation Light Using Wavelength Arb. Units Liquid scintillator emission spectra (scaling arbitrary) Primarily Cherenkov light Goal is to achieve Cherenkov and scintillation separation while losing as few total photons as possible.

Advantages of Long Wavelength Light > 10 meters L. Winslow et. al, 10.1088/1748-0221/9/06/P06012 Using red-sensitive photocathodes improves separation Scattering and absorption lengths increase with wavelength LAB+PPO B. Land In 50kT THEIA, dispersion already gives some separation 40 meters

Our device combines two technologies Winston Cones SNO BOREXINO https://arxiv.org/pdf/physics/0310076.pdf Dichroic Filters Hyper-K proposal C. Rott et al. JINST 12 (2017) ARAPUCA for DUNE Wavelength E. Segreto et al., JINST 13 (2018)

The Dichroicon Complementary to WbLS, slow scintillator, fast photdetectors, etc.

Spectral Sorting with Dichroic Filters 500 nm longpass Demonstration of technology with single dichroic filter T. Kaptanoglu, M. Luo, J. Klein, JINST 14 no. 05 T05001 (2019) LAB+PPO in 90 Sr source UVT acrylic

Spectral Sorting with Dichroic Filters Reflection PMT (short wavelength) Transmission PMT (long wavelength) s s t t i i n n U U . . b Cherenkov b r r A A peak Typical LAB+PPO Scintillation leakage profile Clear Cherenkov separation! Transmission PMT (long wavelength) Photon sorting allows Cherenkov and scintillation separation s t i with high efficiency collection of scintillation light n U . b r A First demonstration of Cherenkov / scintillation Replaced separation using large-area transmission PMT! PMT T. Kaptanoglu, Nucl. Instrum. Meth. A889 (2018) 69-77 T. Kaptanoglu, M. Luo, J. Klein, JINST 14 no. 05 T05001 (2019)

Bench-Top Setup and Simulation Models Dichroicon B. Land M. Luo RAT-PAC Chroma

3D Printed Filter Holder Custom cut short- pass filters from Knight Optical to fill out full 3D printed design High performance short-pass dichroic filters from Edmund Optics Custom cut long- pass filter from Knight Optical to fit the aperture

R1408 8’’ PMT detects light through barrel of dichroicon, equipped with 500 nm shortpass filters Aperture PMTs placed behind 500 nm dichroic longpass filter R2257 R7600-U20

Dichroicon Data with a Cherenkov Source Simultaneous readout 3x increase in Cherenkov light

Dichroicon Data with a LAB+PPO Target LAB+PPO R7600-U20 Scintillation Source ➢ Total Cherenkov light collected (extracted from the fit) is consistent with Cherenkov source data Clear Cherenkov/scintillation ➢ Purity of Cherenkov light in prompt separation window > 90%

Simultaneous Detection of Cherenkov and Scintillation Light Photon sorting allows you to detect Cherenkov light with one PMT and scintillation light with the other, even with overwhelming scintillation light yield 500x more scintillation light Multi-PE scintillation Detected behind dichroicon light at the back Cherenkov light at aperture Detected at aperture Identify Cherenkov and scintillation light in the same event

Dichroicon Data with Liquid Scintillator Targets and Two Different Central Dichroic Filters LAB+PTP LAB+PPO Dichroicon with 500 Dichroicon with 500 nm longpass filter nm longpass filter Dichroicon with 460 nm longpass filter Dichroicon with 460 nm longpass filter Dichroicon filters should be carefully tuned to emission spectrum of scintillator

Dichroicon Data with an Alpha Source Short wavelength light Long wavelength light detected by the R1408 PMT detected by the aperture PMT Expected pulse-shape discrimination for liquid scintillator Additional Particle ID using the Cherenkov light! Improved α/β separation particularly important for background reduction for the low energy program

400 nm Photons Dichroicon B. Land Simulations B. Land 500 nm Photons Chroma 600 nm Photons

Simulations of Large-Scale Detectors With Dichroicons B. Land, Chroma

Conclusions ➢ Spectral sorting of photons has interesting applications for future large-scale water Cherenkov and scintillator detectors, with the potential to improve reconstruction and particle ID ➢ Bench-top measurements of single dichroic filter demonstrated photon-sorting technique ➢ Dichroicon with a Cherenkov source showed photon sorting working as expected ➢ Dichroicon with a scintillation source demonstrated Cherenkov / scintillation separation ➢ Lots of interesting measurements and simulations forthcoming with dichroicons Work supported by Department of Energy Office of High Energy Physics Advanced Detector R&D

Backup Slides

Future Experiments ➢ Several proposed WbLS detectors hoping to achieve Cherenkov and scintillation separation ➢ THEIA is a proposed 50kT WbLS (or equivalent technology) detector, potentially complimentary to DUNE ➢ ANNIE is 26-ton water-based detector measuring neutrino-nucleus interactions. Future phases will likely include LAPPDs and WbLS ➢ WATCHMAN hot-bed for future technologies – WbLS, LAPPDs, fast PMTs, dichroicons THEIA Schematic from J. Klein

Ongoing R&D For Cherenkov / Scintillation Separation CHESS setup at LBNL J. Caravaca et. al, 10.1103/PhysRevC.95.055801 FlatDot at MIT Slow scintillator characterization for Jinping J. Gruszko, et. al, 10.1088/1748-0221/14/02/P02005 Z. Guo et. al, 10.1016/j.astropartphys.2019.02.001 Only timing and isotropy used to identify the Cherenkov light.

90 Sr source LAB+PPO inside UVT acrylic Calculate Δt between the two waveforms Data with no bandpass filter Characterized by intrinsic rise shows typical scintillation τ r ~1ns followed by exponential spectrum decay with τ 1,2,3 ~5ns, ~20ns, ~400ns

Cherenkov / Scintillation Separation With Bandpass Filters Using a set of bandpass filters to span emission spectrum of LAB+PPO R7600-U200 PMTs

Clear Cherenkov peak emerges at long wavelengths

Fitting the Spectrum Simultaneously fit both the Cherenkov and scintillation components of the timing profile Purity, P , of the Cherenkov light in a prompt window > 90% of prompt light is Cherenkov light!

Measuring T(λ, θ) and R(λ, θ) Characterize the transmission and reflection of the dichroic filters as a function of wave and incident angle

Measurements for a 500 nm long-pass dichroic filter + = Very little light lost to the dichroic filter over range of wavelengths and incident angles Used for input into our simulation model